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Structural, morphological and electrochemical properties of long alkoxy-functionalized polythiophene and TiO2 nanocomposites
摘要： High performance alkoxy-functionalized polythiophene (PM4EOT) and TiO2 nanocomposites were prepared via a facile in situ oxidative chemical polymerization of thiophene monomer. The morphology studied demonstrated that nanocomposites were of the core–shell structure with a particle size of approximately 30 nm and PM4EOT shell was of about 2–10 nm thickness. X-ray photoelectron spectroscopy (XPS) spectra proved that there was a new Ti–S interaction between the polymer and TiO2 surface. The supercapacitive behaviors of the nanocomposites investigated by cyclic voltammetry galvanostatic charge–discharge and AC impedance measurements demonstrated that the prepared PM4EOT/TiO2 nanocomposite [1:1 (weight ratio)] exhibits enhanced specific capacitance and cycling stability as compared to the two pristine components and various ratio contents. The specific capacitance of PM4EOT/TiO2 nanocomposite (1:1) was obtained up to 111 F/g at a current density of 0.5 A/g, which is much higher than that of the pure PM4EOT (45 F/g) and TiO2 (1.6 F/g). In addition, the energy density of 15.4 Wh kg?1 and the power density of 308 W kg?1 delivered by composite (1:1) capacitor were achieved at a current density of 0.5 A/g.
关键词： specific capacitance,TiO2 nanocomposites,supercapacitive behaviors,alkoxy-functionalized polythiophene,energy density
更新于2025-09-23 15:21:01
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Petapascal Pressure Driven by Fast Isochoric Heating with a Multipicosecond Intense Laser Pulse
摘要： Fast isochoric laser heating is a scheme to heat matter with a relativistic intensity (> 1018 W=cm2) laser pulse for producing an ultrahigh-energy-density (UHED) state. We have demonstrated an efficient fast isochoric heating of a compressed dense plasma core with a multipicosecond kilojoule-class petawatt laser and an assistance of externally applied kilotesla magnetic fields for guiding fast electrons to the dense plasma. A UHED state of 2.2 PPa is achieved experimentally with 4.6 kJ of total laser energy that is one order of magnitude lower than the energy used in the conventional implosion scheme. A two-dimensional particle-in-cell simulation confirmed that diffusive heating from a laser-plasma interaction zone to the dense plasma plays an essential role to the efficient creation of the UHED state.
关键词： magnetized fast isochoric heating,petapascal pressure,Fast isochoric laser heating,ultrahigh-energy-density state,multipicosecond intense laser pulse
更新于2025-09-23 15:19:57
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Dose-dependent effect of the pulsed Nd:YAG laser in the treatment of crushed sciatic nerve in Wister rats: an experimental model
摘要： The objective of the study was to investigate the efficacy of three energy densities 4, 10, and 50 J/cm2 of pulsed Nd:YAG laser for the treatment of crushed sciatic nerve in Wister rats by evaluating changes in the sciatic functional index and the electrophysiology.A total of 180 Wistar rats were involved in the study. Rats were randomly assigned to five groups. Rats were subjected to the sciatic nerve crushing. Control negative (CONT-ve), which received no crushing; control positive (CONT+ve), which received crushing with no laser; and HILT-4, HILT-10, and HILT-50 groups, which received pulsed Nd:YAG laser (10 Hz, 360 mJ/cm2) with energy densities 4, 10, and 50 J/cm2, respectively. The SFI, the amilitude of compound motor action potential (CMAP) and sciatic motor nerve conduction velocity (MNCV) were measured before and after seven, 14, and 21 days after crushing. For the SFI and electrophysiological analysis, repeated measures ANOVA is used, followed by Bonferroni’s repeated-measures test. Statistical significance was set at p < 0.05. After one week, there was no significant difference in SFI, CMAP, and MNCV among the three laser groups with significant changes between them and CONT-ve and CONT+ve groups. There was a significant increase in either CMAP amplitude or MNCV after 14 days with significant decrease in the SFI after 21 days among all treatment groups. The pulsed Nd:YAG laser applied with energy densities 4, 10, and 50 J/cm2 significantly decreased the SFI and increased the CMAP and MNCV of the crushed sciatic nerve in Wister rats. Among laser doses, the difference in the rate of recovery in the electrophysiology was found after two weeks while in the SFI after three weeks. The improvement after the nerve injury was time and dose dependent.
关键词： Pulsed Nd:YAG laser,Crushing injury,Electrophysiology,Energy density,Sciatic functional index
更新于2025-09-23 15:19:57
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Influence of processing parameters on the density of 316L stainless steel parts manufactured through laser powder bed fusion
摘要： Additive manufacturing technologies are becoming more popular, as they allow the fabrication of specific parts with complex geometries not achievable by conventional manufacturing. In metal additive manufacturing, one of the most widely used technologies is laser powder bed fusion. This work focuses on the influence of different processing parameters on the density of AISI 316L stainless parts obtained through this technology. The article presents a review of published works on the deposition of AISI 316L stainless steel using laser powder bed fusion to define an optimal range of parameters to produce parts with densities above 99%, complemented by density measurements for new sets of laser powder bed fusion processing parameters within the defined optimal range. The investigation provides a further insight on the effect of operating parameters such as vector size and gas atmosphere (Nitrogen and Argon) on the part density. The density measurements were performed using two techniques: micrograph analysis and Archimedes method. Results reveal that an increase in vector size has a negative influence on part density. With the Archimedes method, a maximum relative density of 99.87% was achieved using Nitrogen atmosphere, showing that it is possible to produce near fully dense parts by laser powder bed fusion without post-processing by laser re-melting.
关键词： hatch spacing,gas atmosphere,vector size,energy density,Additive manufacturing,AISI 316L,laser powder bed fusion
更新于2025-09-23 15:19:57
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Preparation, microstructure, and microhardness of selective laser-melted Wa??3Ta sample
摘要： Tungsten (W) alloy is of difficulty in processing for conventional way because of its high melting point. Here, W alloy sample with the addition of 3 wt% Ta was prepared by selective laser melting. The influence of volumetric energy density (VED) on the surface morphology and the relative density was discussed, and microstructure, phase composition, and microhardness were investigated. The results show that a smooth surface and high relative density (95.79%) can be obtained under optimal VED. The W–Ta substitutional solid solution formed because of the replacement of Ta atom. There are strip and block fine grains in the W–3Ta sample with no significant texture. In addition, subgrain structure with a size of around 1 lm formed inside the strip grain, owing to the large thermal gradient and extremely fast cooling rate. Finally, the W–3Ta alloy shows higher microhardness than that obtained by traditional methods.
关键词： tungsten alloy,volumetric energy density,microstructure,microhardness,selective laser melting
更新于2025-09-23 15:19:57
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Ultrahigh Breakdown Strength and Energy Density in PLZST@ PBSAZM Antiferroelectric Ceramics Based on Core-shell Structure
摘要： A novel core-shell structured Pb0.91La0.06(Zr0.552Sn0.368Ti0.08)O3@PbO–B2O3-SiO2-Al2O3-ZnO-MnO2 (PLZST@PBSAZM) antiferroelectric particles were successfully fabricated via sol-gel method. As expected, the sintering temperature was notably reduced from 1250 oC to 1100 oC with the increasing glass contents. More importantly, the breakdown strengths of PLZST@PBSAZM ceramics were significantly increased from 252 kV/cm to 402 kV/cm. As a result, the energy density was up to 7.4 J/cm3 with 1 wt.% of coating glass content, a 55.3% enhancement over the pure PLZST (4.7 J/cm3). Furthermore, the simulations of electric field distribution provided a powerful evidence that the enhancement of the breakdown strength was induced by the core-shell structure, since the glass coating layer could not only undertake the most of electric field, but also impede the grain growth to achieve the smaller grains, which led to the reduction of electric field intensity on the grain cores.
关键词： Core-shell structured,Antiferroelectric,Breakdown strength,Energy density
更新于2025-09-23 15:19:57
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A ternary nanocomposites of graphene / TiO <sub/>2</sub> / polypyrrole for energy storage applications
摘要： Designing a new electrode active materials including graphene and nanomaterials such as Titanium dioxide (TiO2) with polypyrrole have important for supercapacitor devices. In this work, we present a new ternary nanocomposite for using reduced graphene oxide (rGO), TiO2 and polypyrrole (rGO/TiO2/PPy) for supercapacitors. rGO/TiO2/PPy nanocomposites were characterized by the analysis of Fourier transform infrared-attenuated transmission reflectance (FTIR-ATR), Raman spectroscopy, and scanning electron microscopy-energy dispersion X-ray analysis (SEM-EDX). Electrochemical tests were taken by galvanostatic charge/discharge (GCD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies. We have obtained the highest specific capacitance of Csp D 431.23 F/g for [rGO]o/[Py]o D 1/1 at 10 mV/s. A ternary rGO/TiO2/PPy nanocomposite has higher Csp values than Csp D 122.12 F/g at 10 mV/s for rGO/PPy, Csp D 93.17 F/g at 4 mV/s for rGO and Csp D 45.16 F/g at 4 mV/s for GO. A high energy density was obtained as E D 2.03 Wh/kg and power density of P D 18.3 kW/kg for rGO/TiO2/PPy nanocomposite at 1000 mV/s. rGO/TiO2/PPy nanocomposite had a relatively high Coulombic efficiency, as well as a retention of ?100% of its original capacitance for [rGO]o/[Py]o D 1/1 after 1000 cycles. A novel synthesized rGO/TiO2/PPy nanocomposite may be used for supercapacitor devices due to its good electrochemical performances.
关键词： energy density,reduced graphene oxide,circuit model,TiO2,supercapacitor,polypyrrole
更新于2025-09-23 15:19:57
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Understanding strong knocking mechanism through high-strength optical rapid compression machines
摘要： Strong knocking combustion has become the greatest challenge for advanced internal combustion engines to pursue thermal efficiency limits at high power density conditions. Arising from enclosed space and extreme combustion situations, the fundamental mechanism for strong knocking combustion has still not been fully understood. In this study, synchronization measurement was performed through simultaneous pressure acquisition and high-speed direct photography, and knocking experiments were comparatively conducted under spark-ignition (SI) and compression-ignition (CI) conditions in a high-strength optical rapid compression machine (RCM) with flat piston design. Strong knocking phenomena were reproduced through varying initial thermodynamic conditions, and localized autoignition (AI) initiation and reaction wave evolutions were visualized, companied by synchronous pressure and temperature trajectories. The results show that compared with initial temperature, initial pressure and equivalence ratio exhibit greater influence on the variations of knocking severity. The weighting of different contributors can be further quantified by an effective energy density that shows positive but nonlinear correlations with knocking severity. However, the distinctions between CI and SI knocking characteristics at identical effective energy density also reflect the essential role of the interplay between primary flame propagation and end-gas AI progress. Visualized combustion images show that through improving end-gas thermodynamic state and reactivity sensitivity, the primary flame propagation can enhance localized AI initiation and secondary intensive AI evolutions, facilitating combustion mode transitions into developing detonation. The significant influence of primary flame propagation is diminished until ignition delay time becomes sufficiently short. Finally, with estimated thermal heterogeneities in flat-piston RCM configurations, the ignition modes of strong knocking cycles are quantified by a non-dimensional ignition regime diagram, and favorable scaling agreements with strong and mixed ignition regimes are observed.
关键词： Rapid compression machine,Effective energy density,Reaction wave propagation,Strong knocking combustion,Ignition regime
更新于2025-09-19 17:15:36
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Enhanced dielectric property and energy density in poly(vinylidene fluoride-chlorotrifluoroethylene) nanocomposite incorporated with graphene functionalized with hyperbranched polyethylene- <i>graft</i> -poly(trifluoroethyl methacrylate) copolymer
摘要： Polymer film capacitors are attractive as promising candidates for potential applications in compact and efficient electric power systems. The development of a method for producing a polymer nanocomposite with enhanced dielectric property and a high energy density is a fundamental solution for electric storage in a film capacitor. In this work, a hyperbranched polyethylene-graft-poly(trifluoroethyl methacrylate) (HBPE-g-PTFEMA) copolymer was synthesized to exfoliate and functionalize graphene from natural graphite in chloroform on the basis of the CH–π non-covalent stacking between the HBPE-g-PTFEMA stabilizer and graphene. Examination of the morphologies by transmission electron microscopy (TEM) and atomic force microscopy (AFM) confirmed that the resulting graphene had a lateral size of 0.2–0.6 μm and a thickness of around 4 layers. The presence of peaks due to F in the X-ray photoelectron spectroscopy (XPS) spectra of graphene indicates that the fluorinated copolymer was attached to the surface of nanosheets. Few-layer graphene was introduced into a poly(vinylidene fluoride-chlorotrifluoroethylene) (P(VDF-CTFE)) matrix via simple solution casting. The relative content of the electroactive phase in the nanocomposite film increased because the phase transition from the α- to the β-phase was induced by the addition of graphene. The dielectric constant increased to 24.8 with a low dielectric loss of 0.06 at 100 Hz for a 0.8 vol% nanocomposite, and a released energy density of 4.6 J cm?3 with a charge–discharge efficiency of 62% at 250 MV m?1 was achieved with a 0.1 vol% nanocomposite, which was attributed to the combination of the large content of the electroactive phase and interfacial polarization. This strategy based on a nanocomposite with graphene exfoliated by a fluoropolymer sheds light on the mechanism of interfacial polarization and exhibits commendable prospects for applications in flexible film capacitors.
关键词： graphene,poly(vinylidene fluoride-chlorotrifluoroethylene),hyperbranched copolymer,nanocomposite,energy density,dielectric property
更新于2025-09-19 17:15:36
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Single-Walled boron nitride nanotubes interaction with nickel, titanium, palladium, and gold metal atoms- A first-principles study
摘要： Ab initio calculations based on density functional theory was carried out to study the electronic properties of (3,3), (4,2), (5,2) and (6,0) boron nitride nanotubes when interacting with nickel, titanium, palladium and gold metal atoms. These interactions occurred via adsorption, intercalation, nitrogen substitutional doping and boron substitutional doping. The wide band gaps intrinsic to the pristine boron nitride nanotubes were successfully tuned upon interaction with the metal atoms irrespective of the type of interactions. However, for most of the interactions that occurred via intercalation and nitrogen substitutional doping, the boron nitride nanotube was found to possess semi-metallic properties. More states were added in the density of states upon interaction in which the d orbital of the transition metal atoms was found to be the major contributor to the increase in density of states.
关键词： Transition metals,Fermi energy,Density functional theory,Band gap,Boron nitride nanotubes
更新于2025-09-19 17:13:59